Cnidaria-Inspired Morphing Mechanism for Underwater Robot: A Soft Tectonics Approach.

Soft robots demonstrate great potential for underwater exploration, particularly in tasks such as locomotion and biological sampling in fragile marine habitats. However, developing new forms of interaction with underwater life remains a challenge due to inadequate soft mechanisms for studying the behavior of marine invertebrates. We present a 7-cm in diameter anemone robot ("Soromone") capable of performing biological sea anemones' wiggling behavior under the water. Inspired by the body forms of adult cnidaria, we developed a morphing mechanism that serves as both structure and actuator for the Soromone's behavior using a soft tectonics approach-a multistep, multiscale, heterogeneous soft material fabrication technique. As an actuator, the morphing mechanism can precisely control the Soromone via a fluid system; as a structure, it can reinstate the Soromone's original shape by incorporating various degrees of stiffness or softness into a single piece of material during fabrication. Our study demonstrates the advantages of applying a Soromone under water, including increasing water flow for enhanced nutrient uptake, waste removal, and gas exchange. This cnidaria-inspired soft robot could potentially be adapted for interaction with coral reef ecosystems by providing a safe environment for diverse species. Future soft robotics design paradigms based on a soft tectonics approach could expand the variability and applicability of soft robots for underwater exploration and habitation.